<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        /* 原子类 */
        .color-red{color: red};
        .color-green{color: green;}
        .color-yellow{color: yellow;}
        .color-blue{color: blue;}
        .fs28{font-size: 28px;}
        .fs26{font-size: 26px;}
        .fs22{font-size: 22px;}
    </style>
</head>
<body>
    <!-- 直接调用原子类，一目了然 -->
    <p>文字文字文字</p>
    <p class="color-red">class="color-red"</p>
    <p class="color-yellow">class="color-yellow"</p>
    <p class="fs26">class="fs26"</p>
    <p class="color-blue fs22">"color-blue fs22"</p>
</body>
</html>